Hitherto, as separators for disposable articles such as, for example, disposable diapers and napkins and as packaging materials for sanitary articles such as sanitary napkins, etc., various materials are used. For example, as a packaging material for a napkin, a releasing tape and a packaging material each comprising a substrate composed of a flexible plastic film having thereon a releasing agent layer are proposed as described, e.g., in JP-A-3-24949 and JP-A-3-184543 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). However, the substrates used for the foregoing materials are plastic films each composed of a single component, such as polyethylene, polypropylene, polyester, nylon, cellophane, etc., and hence there is a problem that the substrate is too soft or, to the contrary, too hard.
That is, if the substrate is too soft, the substrate is stretched or cut in the conveying step in the production line of napkins, etc., which results in greatly lowering the productivity. Also, if the substrate is too hard, the product such as the releasing tape and the packaging material has a disadvantage that a soft feeling from the point of the practical use is lost and the releasing sound becomes large to lower the commercial value thereof.
Furthermore, from the productivity, when the release treatment surface of the film is smooth, the static friction coefficient and the kinetic friction coefficient become large, whereby the friction at the contact of the film with rolls in the step of producing or packaging articles such as pressure-sensitive adhesive articles and sanitary articles is increased to fall off the releasing agent and cut the film, which become the cause of troubles.